One and two dimensional barcodes are now in common use. The two dimensional barcode in particular has seen popular deployment in signs posted at various locations. A common encoding is the use of the QR code.
Typically, the 2d barcode encodes a URL. A common usage is for a user with a cellphone that has a camera to take a picture of the 2d barcode. Software on the cellphone decodes this to the URL. If the cellphone has (wireless) Internet access, it then goes out on the Internet to that address and downloads the webpage and displays it on the cellphone, in a browser. The user can interact with it as a standard webpage.
A barcode may be preferred over the display of the URL in human readable text, because the latter needs the mobile user to read it and type it into her cellphone browser. The small size of the cellphone screen and the awkwardness of typing letters on the cellphone make the input of the URL error prone.
Hitherto, it appears that from the granted patents and patents pending, as well as general knowledge of the state of the art, that such displays of 2d barcodes are usually in permanent form. For example, printed on a poster or piece of paper.